Rapid exchange stent delivery system

ABSTRACT

Medical devices and methods for making and using the same. An example medical device may include an elongate tubular member, an endosurgery stent disposed on the outer surface of the tubular member, a push tube slidably disposed along the outer surface of the tubular member, and a push member slidably disposed in a lumen formed in the tubular member. The push member may be coupled to the push tube.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/314,778, filed Jun. 25, 2014, which is a continuation of U.S. patentapplication Ser. No. 12/879,448, filed Sep. 10, 2010, now issued as U.S.Pat. No. 8,771,335, which claims priority to U.S. Provisional PatentApplication No. 61/244,301, filed on Sep. 21, 2009, the entiredisclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to medical devices and methods formanufacturing medical devices. More particularly, the present inventionpertains to medical devices for delivering stents to the biliary tractand/or the pancreatic tract.

BACKGROUND

A wide variety of intraluminal medical devices have been developed formedical use, for example, use in the biliary tract. Some of thesedevices include guidewires, catheters, stents, and the like. Thesedevices are manufactured by any one of a variety of differentmanufacturing methods and may be used according to any one of a varietyof methods. Of the known medical devices and methods, each has certainadvantages and disadvantages. There is an ongoing need to providealternative medical devices as well as alternative methods formanufacturing and using medical devices.

BRIEF SUMMARY

The invention provides design, material, manufacturing method, and usealternatives for medical devices or components thereof. An examplemedical device may include an elongate tubular member, an endosurgerystent disposed on the outer surface of the tubular member, a push tubeslidably disposed along the outer surface of the tubular member, and apush member slidably disposed in a lumen formed in the tubular member.The push member may be coupled to the push tube.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present invention.The Figures and Detailed Description which follow more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a partial cross-sectional side view of an example medicaldevice;

FIG. 2A is a top view of a portion of the device depicted in FIG. 1;

FIG. 2B is a top view of another portion of the device depicted in FIG.1;

FIG. 3 is a partially cut-away view of a portion of an example medicaldevice showing a guidewire ramp formed therein;

FIG. 4 is an exploded perspective view of an example medical device andan endosurgery stent;

FIG. 5 is a perspective view of an example medical device with anendosurgery stent coupled thereto; and

FIG. 6 is a perspective view depicting the arrangement of a suturemember relative to a tubular member.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about,” whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

A wide variety of biliary, endoscopic, and/or endosurgical procedureshave been developed for making medical treatments, diagnoses, and imagesof areas along the biliary tract and/or the pancreatic tract. For thepurposes of this disclosure, the “biliary tract” and/or the “pancreatictract” are understood to include various components of the digestivesystem and include, for example, the various ducts of the biliary treebetween the liver and the duodenum as well as the various ducts betweenthe pancreas and the duodenum. Numerous endoscopic and/or endosurgicaldevices have been developed for making medical treatments, diagnoses,and images of areas along the biliary and pancreatic tracts. Some ofthese device and/or procedures include biliary catheters, biliaryguidewires, biliary stent delivery systems, and the like. In general,these devices are guided to the biliary and/or pancreatic tract by anendoscope (and/or a duodenoscope) that is disposed in the duodenum. Oncepositioned, various interventions can be performed depending on theneeds of the patient and the type of device utilized.

FIG. 1 is a partial cross-sectional side view of an example medicaldevice 10, which takes the form of a prosthesis or stent deliverysystem. In at least some embodiments, system 10 may be used to deliverya stent along the biliary or pancreatic tract. However, this is notintended to be limiting. For example, system 10 may be used in a widevariety of applications including applications where drainage (e.g., viaa stent) is desired. This may include urological applications,gynecological applications, etc.

System 10 may include a catheter or tubular member 12 having a firstlumen 14 formed therein, a second lumen 16 formed therein, and an outersurface 18. In some embodiments, tubular member 12 may includeadditional lumens. Tubular member 12 may include a fluid attachment portat its proximal end (not shown). An endosurgical (i.e., a biliary,pancreatic, etc.) prosthesis or stent 20 may be disposed on outersurface 18. A push tube 22 may also be disposed along outer surface 18.Typically, push tube 22 is disposed proximal of stent 20. A push member24 may be slidably disposed in lumen 14. Push member 24 is coupled topush tube 22, for example by an attachment member 26. Attachment member26 may comprise a ring of material that extends around tubular member 18(and underneath push tube 22) and connects push member 24 to push tube22.

Tubular member 12 may also include a guidewire port 28 (also shown inFIG. 2A). Guidewire port 28 may take the form of an opening in the wallof tubular member 12 that provides access to first lumen 14 for anotherdevice such as a guidewire. As such, a guidewire (not shown) may extendalong the exterior of system 10, through port 28, and into and throughlumen 14 prior to, during, or after an intervention. The position ofguidewire port 28 (e.g., near the distal end of tubular member 12) mayallow system 10 to function as a “rapid exchange” type of system that issimilar to typical rapid exchange systems used in the medical devicearts. This feature may be desirable because, for example, it may allowfor rapid and easy exchanges of devices or systems (e.g., system 10)over a guidewire as is typical of rapid exchange systems in other artareas.

System 10 may also include one or more seals or sealing members (notshown) arranged at locations that would help reduce and/or prevent fluidleakage along system 10. Such seals may be disposed along tubular member12, push tube 22, push member 24, junctions between these and/or otherstructures, and/or any other suitable location.

Turning now to FIG. 2A, which illustrates shaft 12 with push tube 22removed, it can be seen that tubular member 12 may include a guidewireport clearance slot or attachment member slot 32 that is generallydisposed adjacent to guidewire port 28. Attachment member clearance slot32 generally provides an opening in the wall of tubular member 12 sothat push tube 22 can slide along outer surface 18 while being connectedwith push member 24. Slot 32 may allow, for example, a portion of pushmember 24, attachment member 26, or another intermediate member disposedbetween push tube 22 and push member 24 to slide therein duringdeployment of stent 20. Similarly, push tube 22 may include a guidewireport slot 30 that may allow push tube 22 to slide along a guidewire(e.g., a guidewire disposed in lumen 14 and/or through port 28) duringdeployment of stent 20 without altering the position or configuration ofthe guidewire as shown in FIG. 2B.

In at least some embodiments, a guidewire ramp 34 may be disposed infirst lumen 14 as illustrated in FIG. 3. Ramp 34 may be formed byskiving tubular member 12, by disposing a structure in lumen 14 thatforms ramp 34, or in any other suitable manner. In FIG. 3, push tube 22is removed so that ramp 34 can be more clearly seen and for simplicity.Guidewire ramp 34 may function by directing a guidewire 36 from firstlumen 14, through guidewire port 28, and through guidewire port slot 30to a position along the exterior of system 10. In at least someembodiments, guidewire ramp 34 may substantially fill a portion of lumen14. This feature may be desirable for a number of reasons. For example,filling lumen 14 may help to ensure that guidewire 36 properly finds itsway out through port 28 without interfering with push member 24 or anyother structure. In addition, filling lumen 14 may also create aphysical barrier that prevents push member 24 from translating too fardistally during an intervention. Thus, ramp 34 may also function as adistal stop. It can be appreciated that when ramp 34 fills lumen 14,ramp 34 may divide lumen 14 into two sections or “sub-lumens” so thattubular member 12 can be thought to have a total of three lumens formedtherein.

Second lumen 16 is generally positioned parallel to first lumen 14 andit may be distinct and independent from first lumen 14. In other words,along tubular member 12 there may be no openings or passageways thatextend between lumens 14/16 such that no fluid communication occursbetween lumens 14/16. As such, second lumen 16 may comprise an injectionlumen and/or an aspiration lumen that can be used independently fromfirst lumen 14. Thus, during a stent placement intervention, first lumen14 can be used as a place for push member 24 to slide and for guidewireplacement and second lumen 16 can be used independently for theinjection of diagnostic and/or treatment materials, the aspiration ofmaterials, or any other suitable use. For example, second lumen 16 canbe used for the injection of contrast material in order to improve thevisualization of system 10 during an intervention. In addition or in thealternative, second lumen 16 (and/or other lumens that may be formed insystem 10) may be utilized to advance other devices to a target siteincluding, for example, sphincterotomes, needles, baskets, and the like,or any other suitable device.

In at least some embodiments, tubular member 12 may have a hub assembly(e.g., a Y type hub assembly) coupled to or otherwise attached at itsproximal end (not shown). The hub assembly may allow for other ancillarydevices to be secured to tubular member 12 and, for example, gain accessto lumen 16. To facilitate such securing of ancillary devices, the hubassembly may include a connector such as a standard luer lock connectoror any other suitable connector. Additionally, the hub assembly mayinclude a locking mechanism for securing the position of guidewire 36.This may allow guidewire 36 to be held stationary, for example, whenpush member 24 is advanced, retracted, or at essentially anyintermediate position.

In use, system 10 may be advanced through an endoscope or duodenoscope(not shown) to a suitable location near a target site. Once positioned,push member 24 can be urged distally, thereby causing push tube 22 toslide distally along outer surface 18 of tubular member 12 and pushstent 20 off of outer surface 18, thereby deploying stent 20.Alternatively, tubular member 12 can be proximally retracted whileholding push member 24 (and, therefore, push tube 22) substantiallystationary, thereby allowing stent 20 to emerge off from tubular member12. In still alternative embodiments, a combination of these twostrategies can be utilized. After deploying stent 20, system 10 can beretracted from the endoscope. Some additional details regarding this andother uses, including variations and/or additions to this use, aredescribed in more detail below.

The movement of push member 24 and/or other structures of system 10 maybe facilitated through the use of a handle (not shown) that may beattached to or formed at the proximal end of system 10. The handle,which may be a soft coated handle that includes a thermoplasticelastomer (TPE), a thermoplastic polyolefin (TPO), or the like, mayinclude one or more structures (e.g., dials, sliders, wheels, buttons,etc.) that may allow the user to easily manipulate the variousstructures of system 10. In some embodiments, a ratchet or ratchetingsystem may also be associated with the handle so that the user canmanipulate the various components of system 10 in a controlled,ratchet-like manner.

Manufacturing system 10 may include a variety of method steps. At leastsome of these steps are determined by the materials selected for thevarious components of system 10. For example, when tubular member 12,push member 24, and/or other components of system 10 are made from anextrudable polymer, the manufacturing of tubular member 12 may includeextrusion of the polymer to form the appropriate structures. Once theextrusion is completed, the various structures can be coupled togetherin any suitable manner to complete the manufacture of system 10.Numerous other methods are contemplated including, for example, molding(including injection molding), casting, and the like.

Variations on these methods are also contemplated when these or othermaterials are utilized including those materials disclosed herein. Ingeneral, system 10 may include a variety of materials including metals,metal alloys, polymers (some examples of which are disclosed below),metal-polymer composites, combinations thereof, and the like, or anyother suitable material. Some examples of suitable metals and metalalloys include stainless steel, such as 304V, 304L, and 316LV stainlesssteel; mild steel; nickel-titanium alloy such as linear-elastic and/orsuper-elastic nitinol; other nickel alloys such asnickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL®625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such asHASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copperalloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS®400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS:R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g.,UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys,other nickel-molybdenum alloys, other nickel-cobalt alloys, othernickel-iron alloys, other nickel-copper alloys, other nickel-tungsten ortungsten alloys, and the like; cobalt-chromium alloys;cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®,PHYNOX®, and the like); platinum enriched stainless steel; combinationsthereof; and the like; or any other suitable material.

As alluded to above, within the family of commercially availablenickel-titanium or nitinol alloys is a category designated “linearelastic” or “non-super-elastic” which, although may be similar inchemistry to conventional shape memory and super elastic varieties, mayexhibit distinct and useful mechanical properties. Linear elastic and/ornon-super-elastic nitinol may be distinguished from super elasticnitinol in that the linear elastic and/or non-super-elastic nitinol doesnot display a substantial “superelastic plateau” or “flag region” in itsstress/strain curve like super elastic nitinol does. Instead, in thelinear elastic and/or non-super-elastic nitinol, as recoverable strainincreases, the stress continues to increase in a substantially linear ora somewhat but not necessarily entirely linear relationship untilplastic deformation begins or at least in a relationship that is morelinear that the super elastic plateau and/or flag region that may beseen with super elastic nitinol. Thus, for the purposes of thisdisclosure linear elastic and/or non-super-elastic nitinol may also betermed “substantially” linear elastic and/or non-super-elastic nitinol.

In some cases, linear elastic and/or non-super-elastic nitinol may alsobe distinguishable from super elastic nitinol in that linear elasticand/or non-super-elastic nitinol may accept up to about 2 to about 5%strain while remaining substantially elastic (e.g., before plasticallydeforming) whereas super elastic nitinol may accept up to about 8%strain before plastically deforming. Both of these materials can bedistinguished from other linear elastic materials such as stainlesssteel (that can also can be distinguished based on its composition),which may accept only about 0.2 to about 0.44% strain before plasticallydeforming.

In some embodiments, the linear elastic and/or non-super-elasticnickel-titanium alloy is an alloy that does not show anymartensite/austenite phase changes that are detectable by DSC and DMTAanalysis over a large temperature range. For example, in someembodiments, there may be no martensite/austenite phase changesdetectable by DSC and DMTA analysis in the range of about −60° C. toabout 120° C. in the linear elastic and/or non-super-elasticnickel-titanium alloy. The mechanical bending properties of suchmaterial may therefore be generally inert to the effect of temperatureover this very broad range of temperature. In some embodiments, themechanical bending properties of the linear elastic and/ornon-super-elastic nickel-titanium alloy at ambient or room temperatureare substantially the same as the mechanical properties at bodytemperature, for example, in that they do not display a super-elasticplateau and/or flag region. In other words, across a broad temperaturerange, the linear elastic and/or non-super-elastic nickel-titanium alloymaintains its linear elastic and/or non-super-elastic characteristicsand/or properties and has essentially no yield point.

In some embodiments, the linear elastic and/or non-super-elasticnickel-titanium alloy may be in the range of about 50 to about 60 weightpercent nickel, with the remainder being essentially titanium. In someembodiments, the composition is in the range of about 54 to about 57weight percent nickel. One example of a suitable nickel-titanium alloyis FHP-NT alloy commercially available from Furukawa Techno Material Co.of Kanagawa, Japan. Some examples of nickel titanium alloys aredisclosed in U.S. Pat. Nos. 5,238,004 and 6,508,803, which areincorporated herein by reference. Other suitable materials may includeULTANIUM™ (available from Neo-Metrics) and GUM METAL™ (available fromToyota). In some other embodiments, a superelastic alloy, for example asuperelastic nitinol, can be used to achieve desired properties.

In at least some embodiments, portions or all of system 10 may also bedoped with, made of, or otherwise include a radiopaque material.Radiopaque materials are understood to be materials capable of producinga relatively bright image on a fluoroscopy screen or another imagingtechnique during a medical procedure. This relatively bright image aidsthe user of system 10 in determining its location. Some examples ofradiopaque materials can include, but are not limited to, gold,platinum, palladium, tantalum, tungsten alloy, polymer material loadedwith a radiopaque filler, and the like. Additionally, radiopaque markerbands and/or coils may be incorporated into the design of system 10 toachieve the same result. In addition, portions or all of system 10 mayinclude markings that may be used to gage the position, for example, oftubular member 12, push tube 22, push member 24, etc. within theanatomy.

In some embodiments, a degree of MRI compatibility is imparted intosystem 10. For example, to enhance compatibility with Magnetic ResonanceImaging (MRI) machines, it may be desirable to make portions or all ofsystem 10 in a manner that would impart a degree of MRI compatibility.For example, portions or all of system 10 may be made of a material thatdoes not substantially distort the image and create substantialartifacts (artifacts are gaps in the image). Certain ferromagneticmaterials, for example, may not be suitable because they may createartifacts in an MRI image. Portions or all of system 10 may also be madefrom a material that the MRI machine can image. Some materials thatexhibit these characteristics include, for example, tungsten,cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®,PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g.,UNS: R30035 such as MP35-N® and the like), nitinol, and the like, andothers.

Some examples of suitable polymers that may be utilized in themanufacturing of system 10 and/or the various components thereof mayinclude polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene(ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, forexample, DELRIN® available from DuPont), polyether block ester,polyurethane, polypropylene (PP), polyvinylchloride (PVC),polyether-ester (for example, ARNITEL® available from DSM EngineeringPlastics), ether or ester based copolymers (for example,butylene/poly(alkylene ether) phthalate and/or other polyesterelastomers such as HYTREL® available from DuPont), polyamide (forexample, DURETHAN® available from Bayer or CRISTAMID® available from ElfAtochem), elastomeric polyamides, block polyamide/ethers, polyetherblock amide (PEBA, for example available under the trade name PEBAX®),ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE),Marlex high-density polyethylene, Marlex low-density polyethylene,linear low density polyethylene (for example REXELL®), polyester,polybutylene terephthalate (PBT), polyethylene terephthalate (PET),polytrimethylene terephthalate, polyethylene naphthalate (PEN),polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI),polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polyparaphenylene terephthalamide (for example, KEVLAR®), polysulfone,nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon),perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin,polystyrene, epoxy, polyvinylidene chloride (PVdC), polycarbonates,ionomers, biocompatible polymers, poly(L-lactide) (PLLA),poly(D,L-lactide) (PLA), polyglycolide (PGA),poly(L-lactide-co-D,L-lactide) (PLLA/PLA), poly(L-lactide-co-glycolide)(PLLA/PGA), poly(D, L-lactide-co-glycolide) (PLA/PGA),poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polyethylene oxide(PEO), polydioxanone (PDS), polycaprolactone (PCL), polyhydroxylbutyrate(PHBT), poly(phosphazene), polyD,L-lactide-co-caprolactone) (PLA/PCL),poly(glycolide-co-caprolactone) (PGA/PCL), polyanhydrides (PAN),poly(ortho esters), poly(phosphate ester), poly(amino acid),polyacrylate, polyacrylamid, poly(hydroxyethyl methacrylate),polyurethane, polysiloxane and their copolymers, or mixtures orcombinations thereof.

FIGS. 4-6 illustrate some additional features of system 10 as well asdepict how stent 20 may be coupled to and held on tubular member 12.Stent 20, as depicted in FIG. 4, may comprise a polymeric tube orcylinder with a central lumen (so that stent 20 can be fitted overtubular member 12) and one or more slots formed therein that form adefine one or more flaps 38 along the exterior thereof. For example,stent 20 may include a proximal flap 38 (as shown) and a distal flap(not shown) that is similar to proximal flap 38. Flaps 38 may providestent 20 with a number of desirable features. For example, flaps 38(e.g., a distal flap) can be disposed within the bile duct or pancreasduct and prevent migration of stent 20 out of the duct during anintervention. Another flap (e.g., a proximal flap) may remain outside ofthe duct, for example in the duodenum, and prevent migration of stent 20into the duct during the intervention. Prior to delivery, flaps 38 maybe held flat by a suitable sheath of material so that system 10 can beloaded into an endoscope. During delivery of stent 20, flaps 38 may beheld flat within the endoscope. After emerging from the endoscope, flaps38 may resume their shape (e.g., as illustrated in FIG. 4).

It can be appreciated that stent 20, which takes the form of anendosurgical (e.g., biliary and/or pancreatic) stent 20 differs fromintravascular stents. For example, stent 20 is typically made from apolymeric material and is typically delivered in a “normal” ornon-compressed state. Conversely, intravascular stents are typicallydelivered in a compressed stated (e.g., compressed onto a catheterand/or a balloon) and then expanded by a balloon and/or by virtue oftheir material composition (e.g., when made from self-expanding shapememory materials such as nitinol). Other distinctions between stent 20and intravascular stents can be appreciated by those with ordinary skillin the art.

In order to improve the attachment or coupling between stent 20 andtubular member 12 during delivery, a suture member 40 may be used.Suture member 40 may be any type of suture or suturing structure and/orany other suitable structure that may include a loop. Suture member 40may be strung through one or more suture openings 42 on push tube 22 andformed into a loop. The free end of suture member 40 (e.g., the loop)may be disposed in the opening of stent 20 that is defined at flap 38 asillustrated in FIG. 5. Tubular member 12 may enter the lumen of stent 20and pass through the loop of suture member 40. This arrangement isdepicted in FIG. 6 in the absence of stent 20. This arrangement willessentially “trap” stent 20 between tubular member 12 and push tube 22.To deploy stent 20, push tube 24 may be distally advanced and/or tubularmember 12 may be proximally withdrawn so that tubular member 12withdraws out from the loop of suture member 40, thereby “freeing” stent20 from suture member 40. The arrangement of the various structures ofsystem 10 may vary. In some embodiments, system 10 may include any ofthe structures or utilize any of the arrangements of structures that aredisclosed in U.S. Pat. Nos. 5,334,185 and 5,152,749, the entiredisclosures of which are herein incorporated by reference.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of theinvention. The invention's scope is, of course, defined in the languagein which the appended claims are expressed.

What is claimed is:
 1. A stent delivery system, comprising: a stenthaving a lumen formed therein and an opening; a push tube having a lumenformed therein, with the stent in a loaded condition abutting a distalend of the push tube; an elongate tubular member extendable through thelumen of the push tube and the lumen of the stent; and a memberextending from the push tube and forming a loop disposable through theopening of the stent and around an inner circumference of the stentlumen, the elongate tubular member passable through the lumen of thestent and the loop of the member in the loaded condition.
 2. The stentdelivery system of claim 1, wherein the member is a suture.
 3. The stentdelivery system of claim 1, wherein the push tube includes an opening,and the member extends from the push tube opening.
 4. The stent deliverysystem of claim 1, wherein in the loaded condition the elongate tubularmember is slidably disposed within the lumen of the push tube and thelumen of the stent.
 5. The stent delivery system of claim 1, wherein thestent is coupled to the push tube when the elongate tubular member ispassed through the loop of the member within the inner circumference ofthe lumen of the stent.
 6. The stent delivery system of claim 1, whereinthe stent is uncoupled from the push tube in an unloaded condition whenthe elongate tubular member is withdrawn from the loop of the member andfrom within the inner circumference of the lumen of the stent.
 7. Thestent delivery system of claim 1, wherein the elongate tubular memberincludes a lumen formed therein.
 8. The stent delivery system of claim7, further comprising a guidewire, and wherein the lumen of the elongatetubular member is configured to receive the guidewire therethrough. 9.The stent delivery system of claim 1, wherein the stent includes one ormore slots formed therein defining one or more flaps.
 10. The stentdelivery system of claim 9, wherein the opening of the stent comprisesone of the flaps.
 11. A stent delivery system, comprising: a stenthaving a lumen formed therein and an opening; a push tube having a lumenformed therein, with the stent abutting a distal end of the push tube; acatheter extendable through the lumen of the push tube and the lumen ofthe stent; and a member extending from the push tube and forming a loopdisposable in the opening of the stent, wherein the catheter isconfigured to enter the lumen of the stent and the loop of the member toreleasably couple the stent to the catheter.
 12. The stent deliverysystem of claim 11, wherein the member is a suture.
 13. The stentdelivery system of claim 11, wherein the catheter is slidably disposedwithin the lumen of the push tube and the lumen of the stent.
 14. Thestent delivery system of claim 11, wherein the stent is uncoupled fromthe push tube when the catheter is withdrawn from the loop of the memberand from within the lumen of the stent.
 15. The stent delivery system ofclaim 11, wherein the catheter includes a lumen formed therein.
 16. Thestent delivery system of claim 11, wherein the stent includes one ormore slots formed therein defining one or more flaps.
 17. The stentdelivery system of claim 16, further comprising a sheath removablydisposed over the one or more flaps to hold the one or more flapsagainst the stent.
 18. The stent delivery system of claim 1, wherein thestent is a drainage stent.
 19. A method of delivering a stent,comprising: introducing a stent delivery system into a patient, whereinthe stent delivery system includes: a stent having a lumen formedtherein and an opening, a push tube having a lumen formed therein, withthe stent abutting a distal end of the push tube, a member extendingfrom the push tube and forming a loop through the opening of the stentand around an inner circumference of the stent lumen, and an elongatetubular member slidably disposed within the lumen of the push tube andthe lumen of the stent and extending through the loop of the member; andremoving the elongated tubular member from within the lumen of the stentand the loop of the member to uncouple and deliver the stent from theelongate tubular member within the patient.
 20. The method of claim 19,further comprising removing the push tube and elongate tubular memberfrom the patient.